The present invention relates to a guide vane assembly for a gas turbine engine and in particular relates to a fan outlet guide vane assembly for a turbofan gas turbine engine.
A fan outlet guide vane of a gas turbine engine currently comprises a plurality of fan outlet guide vanes, a casing and a plurality of panels. The fan outlet guide vanes are circumferentially spaced, are secured at their radially outer ends to the casing and extend radially inwardly from the casing. The panels are secured to the casing. Each panel is arranged between two adjacent fan outlet guide vanes to define the flow path between the fan outlet guide vanes. The panels are secured to the casing by fasteners, for example nuts and radially extending bolts or by an adhesive bond and fasteners.
A problem with the current design is that there is a pressure difference between the radially inner faces and the radially outer faces of the panels, which tends to remove the panels from the casing. Additionally the fan outlet guide vane assembly provides no noise reduction features to minimise noise produced by the turbofan gas turbine engine.
Accordingly the present invention seeks to provide a novel guide vane assembly which reduces, preferably overcomes, the above mentioned problems.
Accordingly the present invention provides a guide vane assembly comprising a casing, a plurality of circumferentially spaced radially extending guide vanes, the guide vanes being secured at their radially outer ends to the casing, a plurality of panels being secured to the casing, each panel being arranged between two adjacent guide vanes to define the flow path between the guide vanes, at least one panel comprising a perforated skin and an acoustic treatment structure, the perforated skin defining the flow path between the guide vanes.
Preferably each panel comprises a perforated skin and an acoustic treatment structure, the perforated skin defining the flow path between the guide vanes.
Preferably the at least one panel is secured to the casing by fasteners or by an adhesive bond and fasteners.
Preferably the perforated skin of the at least one panel comprises a composite material. Preferably the at least one perforated skin comprises a
Preferably the acoustic treatment structure comprises a honeycomb structure. Preferably the honeycomb structure comprises a plurality of cells, each cell having eight sides or less.
Preferably the honeycomb structure comprises an aluminium honeycomb, a composite material honeycomb or other suitable honeycomb.
Preferably the guide vanes are secured to the casing by fasteners or by welded joints.
Preferably a flexible seal is arranged between the circumferential edges of the at least one panel and the two adjacent guide vanes to seal the gap between the circumferential edges of the at least one panel and the two adjacent guide vanes.
Preferably the guide vanes are fan outlet guide vanes and the casing is a fan casing.
The perforated skin and the acoustic treatment structure may be integral.
The perforated skin and the acoustic treatment may comprise a composite material or a metal.
The perforated skin and the acoustic treatment may comprise aluminium or glass fibre reinforced nylon.
The acoustic treatment may be provided with drainage apertures to allow water and/or lubricant to flow generally axially and to prevent water and/or lubricant flowing generally circumferentially between the panel and the casing between the two adjacent guide vanes.